The undercover reporter known as the "Fake Sheikh" tampered with evidence after trying to set up former X Factor judge Tulisa Contostavlos in a drugs sting, a court heard.

Mazher Mahmood, 53, is alleged to have urged his former driver, 67-year-old Alan Smith, to change a witness statement that suggested the former N-Dubz star was anti-drugs.

Tulisa, 28, was targeted in December 2012 by the self-styled "king of the sting", who posed as an influential film producer offering her a role in a blockbuster Hollywood film.

Mahmood took the aspiring actress on a trip to Las Vegas and to London restaurants before asking her to supply him with cocaine.

He would lure his target with a fictional story, deceiving them into believing he was someone who could offer them something they wantedprosecutor Sarah Forshaw

The singer went on trial in July 2014 for allegedly being concerned in the supply of cocaine after the story was published in The Sun on Sunday newspaper.

Prosecutor Sarah Forshaw told the jury of six men and six women at the Old Bailey: "Mazher Mahmood had a considerable interest in the prosecution succeeding in terms of his reputation and his standing.

"He had created a good deal of publicity about Tulisa before the police had even had an opportunity to arrest her."

Mahmood, who previously worked for the defunct News of the World and The Sunday Times, is on trial accused of conspiring to pervert the course of justice.

He arrived at court on Wednesday flanked by two bodyguards with the hood of his navy blue anorak pulled up and his face covered. But he appeared in open court wearing a suit as he sat next to Smith.

Undercover reporter Mazher Mahmood (centre) at the Old Bailey with his face coveredCredit:
John Stillwell/PA

The pair are charged with conspiring together for Smith to "change the content of a draft statement to the police, with intent to pervert the course of justice".

"This is a case about an agreement made between these two individuals to tamper with evidence in a criminal trial," said the prosecutor as she opened the case.

"It happened back in June 2014. Facing trial was a celebrity, Tulisa Contostavlos - a singer and aspiring actress, perhaps best known for her membership of a hit pop group called N-Dubz and her appearances as a judge on a television programme, the X Factor.

"Ms Contostavlos faced an allegation that she had arranged for the supply of half an ounce of cocaine.

"The first defendant, Mazher Mahmood, had a vested interest in the outcome of the criminal proceedings against her.

"Why? He was an undercover reporter working for a tabloid newspaper, The Sun, and it was he who tried to set her up to commit a criminal offence in the first place."

Retired driver Alan Smith arrives at the Old Bailey on WednesdayCredit:
Philip Toscano/PA

The prosecutor said jurors might have heard of Mahmood as the Fake Sheikh because of his elaborate disguises.

"He would lure his target with a fictional story, deceiving them into believing he was someone who could offer them something they wanted - a part in a blockbuster movie for example.

"Then, when that targeted individual wishes to impress him, he would invite them to take part in a criminal offence.

"So it was with Tulisa Contostavlos. He asked her to arrange for him to be supplies with a Class A drug - cocaine. He carried a secret recording device.

"One he had his explosive story, he handed some of his evidence over to police and became a witness for the prosecution against Tulisa Contostavlos, the defendant."

Alan Smith (left) and Mazher Mahmood are pictured in the dock at the Old Bailey in a court artist sketchCredit:
Elizabeth Cook/PA

The court heard Smith was a driver, who had been working for Mahmood for many years.

"Together, they conspired to change a written statement that Mr Smith had provided to a police officer in the run up to the trial of Tulisa Contostavlos," Ms Forshaw added.

"The original statement that Mr Smith had made to the police contained some evidence that may have assisted those defending Tulisa.

"Mr Smith had told the police officer taking his statement he remembered driving Tulisa and two friends home from a meeting with Mr Mahmood.

"Tulisa had spoken about someone in her family being dependent on cocaine and Mr Smith had told the officer Tulisa had seemed really negative about cocaine and expresses her disapproval of drugs."